The technology behind inverters is well documented. Inverters typically feature an enclosure whose back panel is mounted to the wall of a building or other structure. Due to the electric and electronic components (e.g. coils) inside the enclosure, the inverter generates heat that needs to be dissipated. The inverter enclosure is therefore outfitted with fans that cool the component parts within. In addition, the back panel of this type of inverter typically features cooling fins that also help to dissipate heat. Heat is thereby absorbed by the ambient air that flows along the back panel of the enclosure.
This type of inverter can also feature fans on the back panel of the enclosure to facilitate air circulation and thus allow for improved cooling of the area around the back panel. Because these fans require power, they must be supplied with electricity from the inside of the inverter enclosure via a plug. The hole through which the plug is inserted into the enclosure always poses the risk of moisture ingress.
This type of fan can become dirty and the only way to access the fan for cleaning or replacement is from the back panel, which means the entire inverter needs to be removed from the wall first.
The upshot of this is that, for a variety of applications, the fans on the back panel need to be mounted externally so as to ensure sufficient inverter cooling while also allowing easy access for cleaning purposes when the back panel of the inverter is attached to a wall.
One disadvantage of this configuration is that it requires an entry way or opening to the inside of the inverter in order to supply power to the fan. This naturally increases the risk of moisture entering the enclosure.